Electronic ignition enhancing circuit having both fundamental and harmonic resonant circuits as well as a DC offset
First Claim
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1. A ballast circuit for igniting and operating a discharge lamp, the circuit comprising:
- a transformer having a primary winding and a variable flux linked secondary winding connected to a discharge lamp, said primary winding being connected to a driver circuit, said secondary winding being connected in series with said lamp through a capacitor having a capacitance such that a first resonant circuit having an essentially zero reactance with respect to said lamp results after ignition of said lamp;
a driver circuit connected to said primary winding for driving said transformer at a sufficiently high frequency to initiate and to maintain a stable arc in the operation of said lamp connection to said secondary winding;
an ignition circuit including a direct current offset circuit and a second resonant circuit, said ignition circuit being connected between said transformer and said lamp;
said second resonant circuit establishes a resonance at one of the harmonics of said second resonant circuit prior to ignition of said lamp; and
said direct current offset circuit applies a non-oscillatory voltage to said lamp in combination with an oscillatory voltage applied to said lamp by said second resonant circuit;
wherein said combination of oscillatory and non-oscillatory voltages applied to said lamp reduces the voltage otherwise required for ignition of said lamp.
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Abstract
A high frequency electronic ballast (128) having a transformer (104) in which the transformer (104) has a primary winding (106) which is coupled to a secondary winding (108) via a primary flux path (1) from which flux can be diverted by a secondary flux path (2) including an air gap (114) which can be adjustable. Use of the transformer (104) permits load operation from a rectified alternating current power source which can be compensated by a high frequency power supply (192) to present a favorable power factor to the alternating current supply.
55 Citations
25 Claims
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1. A ballast circuit for igniting and operating a discharge lamp, the circuit comprising:
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a transformer having a primary winding and a variable flux linked secondary winding connected to a discharge lamp, said primary winding being connected to a driver circuit, said secondary winding being connected in series with said lamp through a capacitor having a capacitance such that a first resonant circuit having an essentially zero reactance with respect to said lamp results after ignition of said lamp; a driver circuit connected to said primary winding for driving said transformer at a sufficiently high frequency to initiate and to maintain a stable arc in the operation of said lamp connection to said secondary winding; an ignition circuit including a direct current offset circuit and a second resonant circuit, said ignition circuit being connected between said transformer and said lamp; said second resonant circuit establishes a resonance at one of the harmonics of said second resonant circuit prior to ignition of said lamp; and said direct current offset circuit applies a non-oscillatory voltage to said lamp in combination with an oscillatory voltage applied to said lamp by said second resonant circuit; wherein said combination of oscillatory and non-oscillatory voltages applied to said lamp reduces the voltage otherwise required for ignition of said lamp. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification